The purpose of this study was to describe the results of postoperative sole interstitial
brachytherapy (BT) in patients with resectable floor of mouth tumors.Between January
1998 and December 2017, 44 patients with squamous cell histology, stage T1-3N0-1M0
floor of mouth tumor were treated by excision of the primary lesion with or without
neck dissection followed by sole high-dose-rate tumor bed BT with an average dose
of 22.7 Gy (10-45 Gy) using rigid metal needles (n = 14; 32%) or flexible plastic
catheters (n = 30; 68%).During a median followup time of 122 months for surviving
patients, the probability of 5- and 10-year local and regional tumor control, overall
survival (OS), and disease-specific survival (DSS) was 89% and 89%, 73% and 67%, 52%
and 32%, 66% and 54%, respectively. In univariate analysis, lymphovascular invasion
was a negative predictor of regional tumor control (p = 0.0062), DSS (p = 0.0056),
and OS (p = 0.0325), whereas cervical recurrence was associated with worse DSS (p
< 0.0001) and OS (p < 0.0001). The incidence of local Grade 1, 2, and 3 mucositis
was 25%, 64%, and 11%, respectively. Grade 4 side effect, that is soft tissue necrosis
occurred in four cases (9%).Results of postoperative sole high-dose-rate BT of floor
of mouth tumors are comparable with those reported with low-dose-rate BT, and this
method could improve local tumor control and DSS compared with exclusive surgical
treatment.
